e2e tests should be multizone aware

Pass MULTIZONE=true env. variable to e2e test framework.

hack/ginkgo-e2e.sh

@@ -133,6 +133,7 @@ export PATH=$(dirname "${e2e_test}"):"${PATH}"
   --provider="${KUBERNETES_PROVIDER}" \
   --gce-project="${PROJECT:-}" \
   --gce-zone="${ZONE:-}" \
+  --gce-multizone="${MULTIZONE:-false}" \
   --gke-cluster="${CLUSTER_NAME:-}" \
   --kube-master="${KUBE_MASTER:-}" \
   --cluster-tag="${CLUSTER_ID:-}" \

hack/verify-flags/known-flags.txt

@@ -281,6 +281,7 @@ garbage-collector-enabled
 gather-logs-sizes
 gather-metrics-at-teardown
 gather-resource-usage
+gce-multizone
 gce-project
 gce-service-account
 gce-upgrade-script

test/e2e/e2e.go

@@ -72,7 +72,10 @@ func setupProviderConfig() error {
 		if err != nil {
 			return fmt.Errorf("error parsing GCE/GKE region from zone %q: %v", zone, err)
 		}
-		managedZones := []string{zone} // Only single-zone for now
+		managedZones := []string{} // Manage all zones in the region
+		if !framework.TestContext.CloudConfig.MultiZone {
+			managedZones = []string{zone}
+		}
 		cloudConfig.Provider, err = gcecloud.CreateGCECloud(framework.TestContext.CloudConfig.ProjectID, region, zone, managedZones, "" /* networkUrl */, nil /* nodeTags */, "" /* nodeInstancePerfix */, nil /* tokenSource */, false /* useMetadataServer */)
 		if err != nil {
 			return fmt.Errorf("Error building GCE/GKE provider: %v", err)

test/e2e/framework/test_context.go

@@ -129,6 +129,7 @@ type NodeTestContextType struct {
 type CloudConfig struct {
 	ProjectID         string
 	Zone              string
+	MultiZone         bool
 	Cluster           string
 	MasterName        string
 	NodeInstanceGroup string
@@ -194,6 +195,7 @@ func RegisterClusterFlags() {
 	flag.StringVar(&cloudConfig.MasterName, "kube-master", "", "Name of the kubernetes master. Only required if provider is gce or gke")
 	flag.StringVar(&cloudConfig.ProjectID, "gce-project", "", "The GCE project being used, if applicable")
 	flag.StringVar(&cloudConfig.Zone, "gce-zone", "", "GCE zone being used, if applicable")
+	flag.BoolVar(&cloudConfig.MultiZone, "gce-multizone", false, "If true, start GCE cloud provider with multizone support.")
 	flag.StringVar(&cloudConfig.Cluster, "gke-cluster", "", "GKE name of cluster being used, if applicable")
 	flag.StringVar(&cloudConfig.NodeInstanceGroup, "node-instance-group", "", "Name of the managed instance group for nodes. Valid only for gce, gke or aws. If there is more than one group: comma separated list of groups.")
 	flag.StringVar(&cloudConfig.Network, "network", "e2e", "The cloud provider network for this e2e cluster.")